The writer wishes to comment on some aspects of the geology, petrology and geochemistry of the paper by Van Tonder and Mouri (2010) that are deemed to be problematic. In their paper the authors have chosen to subdivide the Johannesburg Dome (JD) granitoids into three main suites, namely:

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This subdivision differs from earlier explanations of the geology of the granitic rocks on the dome (Anhaeusser, 1971; 1973). Under normal circumstances, when presenting new interpretations of previously studied geological environments, it is customary to provide new data and argument in support of any suggested changes to the geological...